DNS Discovery Flapping

Every now and then we see multiple backends flapping with this messages

is going DOWN for maintenance (entry removed from SRV record)

And sometimes when this message appears, traffic goes to BUSY for brief amount of time.

I couldn’t see any dns requests being failed, but we still see this flaps.

This is a gist of haproxy config

  user haproxy
  group haproxy
  nbproc 1
  nbthread 16
  cpu-map auto:1/1-16 0-15
  log /dev/log local2
  log /dev/log local0 notice
  chroot /path/to/haproxy
  pidfile /path/to/haproxy.pid
  maxconn 200000
  hard-stop-after 1h
  stats socket /path/to/haproxy/stats mode 660 level admin expose-fd listeners
  tune.ssl.cachesize 3000000
  tune.ssl.lifetime 60000
  ssl-default-bind-options ssl-min-ver TLSv1.2 ssl-max-ver TLSv1.2
  server-state-file /path/to//haproxy_server_states
  tune.bufsize 40960

resolvers mydns
        nameserver dns1 stream+ipv4@
        accepted_payload_size 65535 # allow larger DNS payloads
        timeout resolve 1s
        timeout retry   2s
        hold other    50000s
        hold refused  50000s
        hold timeout  50000s
        hold nx       5s
        hold valid    1s
        hold obsolete 1s

frontend listener
        bind x.x.x.x:80 mss 1440 alpn h2,http/1.1
        mode http
        default_backend server_group

backend server_group
        mode  http
        server-template template_name 30 _servers-0._tcp.servers.local init-addr last,libc,none resolvers mydns check  port 80  maxconn 2000 maxqueue 1
        errorfile 503 /path/to/static/busy-json.http

Kindly help if we are doing something wrong !